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Message: [QUOTE="Bombastus, post: 91736, member: 2178"] General MIDI defines 128 melodic program assignments, yet it does not require two compatible sound generators to use the same recordings or synthesis. A file can ask both devices for the same piano and still get two noticeably different pianos. The useful distinction is between the performance data and the sound engine. Notes, velocities, controller moves, program changes, and timing can survive intact while the playback device supplies its own samples, envelopes, filters, effects, and gain structure. Once you understand [B][URL='https://goldmidi.com/community/resources/what-is-midi.658/']how MIDI controls musical instruments[/URL][/B], the remaining mystery usually sits in how those instructions are interpreted. A second source of confusion lives inside the file itself. Many MIDI files carry setup messages near the beginning, so choosing a sound manually before pressing play does not guarantee your choice will survive the first second. [HEADING=2]General MIDI standardizes names more than tone[/HEADING] General MIDI solved an important compatibility problem by assigning standard instrument identities to program numbers. A compatible file can request an acoustic grand piano, violin, trumpet, or other defined sound without knowing the exact synthesizer that will play it. Percussion also receives a standardized note mapping in the General MIDI setup. The standard does not freeze the acoustic result. One sound module might build its piano from short sampled attacks, another might use a larger multisample set, and a software player might render the same program through an entirely different library. Velocity layers, envelopes, filtering, stereo width, reverb, and output processing can all change the impression while the requested program remains correct. Older games make the difference obvious because the composition may be identical while the playback hardware changes character completely. The melody, harmony, note lengths, and program requests can match, yet the balance between instruments can shift enough to expose or bury parts of the arrangement. Instrument numbering can also look inconsistent inside software. MIDI data represents Program Change values from 0 through 127, while some interfaces display the same choices as 1 through 128 for humans. A one-step display difference is not automatically a corrupt file, but manually editing the wrong value can select a neighboring patch. [HEADING=2]Bank and reset messages can change the result first[/HEADING] Program Change is only part of sound selection on devices with more than 128 patches. Bank Select uses controller numbers 0 and 32 for the bank values, after which a Program Change can choose a program within the selected bank. Hardware makers do not all organize their extended sound sets the same way. A file created for a particular module can therefore request a bank that another synth interprets differently, ignores, or cannot reproduce. General MIDI material is more portable when it stays within the common mapping, while GS, XG, GM2, and manufacturer-specific extensions can depend on capabilities outside basic GM1 playback. System Exclusive setup messages add another layer. A GM System On message can initialize a compatible sound generator into its General MIDI state, resetting settings before the arrangement begins. Other formats use their own mode-setting messages, and unsupported SysEx may simply be ignored by a different playback engine. This is why changing a patch in your player can appear to work until playback starts. A Program Change or setup message stored at the beginning of the sequence may immediately select something else. An early [B][URL='https://patents.google.com/patent/EP0484043B1/en']MIDI voice translation system[/URL][/B] addressed the same portability problem by mapping standardized voice information to synthesizer-specific sound numbers instead of assuming every unit organized voices identically. [HEADING=2]Controllers can make matching patches sound unrelated[/HEADING] Patch selection is not the end of the story. A MIDI file can also carry channel volume, expression, pan, sustain, modulation, pitch bend, effect-send values, and other controller information that changes how the selected sound behaves. Different playback systems may support different subsets or apply them with different internal scaling. A piano that seems weak on one player may not be the wrong piano at all. Low expression, different reverb handling, a lingering controller state, or an ignored reset can change the balance before you start blaming the sound bank. Imported files are especially worth checking in an event list because setup data can sit several measures away from the notes you are editing. Drums expose compatibility problems quickly. General MIDI gives percussion a common note layout, but extensions can offer extra kits, altered mappings, and additional percussion behavior. A player limited to basic GM may fall back to its standard kit while another device follows bank and program information intended for a richer format. The cleanest comparison uses the same MIDI data with each playback system freshly initialized, then checks mode, bank, program, and controller state before judging the tone itself. If the requested instruments match but the character still changes, the difference belongs to the sound generator rather than the sequence. [/QUOTE]

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